Once again, it's mee

User23

3

Hi maths experts, Ok so i came across this question and I came up with an answer, idk if it's correct. i got 150.2587..

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Reply 1

username1732133

15

Original post by User23

Hi maths experts, Ok so i came across this question and I came up with an answer, idk if it's correct. i got 150.2587..

Would you like to show some working so that we can see where you went wrong?

Reply 2

nucdev

18

Original post by User23

Hi maths experts, Ok so i came across this question and I came up with an answer, idk if it's correct. i got 150.2587..

I got something near the high 90s around 97.something - but I did that without pen & paper.

Reply 3

troubadour.

19

Original post by User23

Hi maths experts, Ok so i came across this question and I came up with an answer, idk if it's correct. i got 150.2587..

I got a different answer. I'm not supposed to give full answers so I'll try to guide you. :smile:

What do you think the first step is? Talk us through the working and we'll see where you went wrong.

Reply 4

troubadour.

19

Original post by nucdev

I got something near the high 90s around 97.something - but I did that without pen & paper.

Same.

Reply 5

User23

OP

3

Original post by BuryMathsTutor

Would you like to show some working so that we can see where you went wrong?

Oh damn it's wrong?! Ok, so this was my working out:
So since the area of the square is 84.5cm^2 i square rooted this to get the sides and this gave me 9.1923.. then i assumed that the height of the trapezium is 9.1923 and to find out the longer length of the trapezium i did 11.75+9.1923..= 20.9423 then i used 1/2(a+b)h so, 1/2(11.75+20.9423)9.1923 which gave me 150.2587

Reply 6

User23

OP

3

Original post by nucdev

I got something near the high 90s around 97.something - but I did that without pen & paper.

HOW?

Reply 7

User23

OP

3

Ok i got it i got it!!

Reply 8

User23

OP

3

Original post by hydeman

same.

i got 97.4981!!!

Reply 9

nucdev

18

Original post by User23

i got 97.4981!!!

Excellent - around about what I got.

Reply 10

troubadour.

19

Original post by User23

i got 97.4981!!!

Nice one! Did you you round the awkward number you get by square rooting 84.5? It later gives a clean 1 d.p. number when you use trigonometry and the final answer I got was exactly 97.5 cm² although yours is so close that I don't think any examiner would care.

Edit: Out of interest, what level is this? Is it GCSE, A Level, or one of the Scottish/Irish equivalents of those?

(edited 8 years ago)

Reply 11

nucdev

18

Original post by Hydeman

Nice one! Did you you round the awkward number you get by square rooting 84.5? It later gives a clean 1 d.p. number when you use trigonometry and the final answer I got was exactly 97.5 cm² although yours is so close that I don't think any examiner would care.

Yeah that's probably what she did - I did that as well only because I had a basic calculator and no pen & paper and got a long decimal.

Reply 12

username1828143

1

Original post by Hydeman

Nice one! Did you you round the awkward number you get by square rooting 84.5? It later gives a clean 1 d.p. number when you use trigonometry and the final answer I got was exactly 97.5 cm² although yours is so close that I don't think any examiner would care.

Edit: Out of interest, what level is this? Is it GCSE, A Level, or one of the Scottish/Irish equivalents of those?

This is from the 2014 Maths II Westminster 13+ scholarship entry paper.

You can find them here: https://www.westminster.org.uk/admissions/scholarships-bursaries (scroll to the bottom)

Reply 13

chazwomaq

18

Original post by User23

Oh damn it's wrong?! Ok, so this was my working out:
So since the area of the square is 84.5cm^2 i square rooted this to get the sides and this gave me 9.1923.. then i assumed that the height of the trapezium is 9.1923 and to find out the longer length of the trapezium i did 11.75+9.1923..= 20.9423 then i used 1/2(a+b)h so, 1/2(11.75+20.9423)9.1923 which gave me 150.2587

This was your mistake I think. That length is of the hypotenuse of the triangle, not of the other sides. So a little trigonometry is in order. Or Pythagoras.

I also got about 97.5 cm^2.

(edited 8 years ago)

Reply 14

username1828143

1

Original post by User23

Hi maths experts, Ok so i came across this question and I came up with an answer, idk if it's correct. i got 150.2587..

I know you've already figured it out, but here's my solution anyway :smile:

Reply 15

troubadour.

19

Original post by boojiebaba

This is from the 2014 Maths II Westminster 13+ scholarship entry paper.

You can find them here: https://www.westminster.org.uk/admissions/scholarships-bursaries (scroll to the bottom)

Ah, alright. So it's roughly GCSE-level. :smile:

I've already finished school so not much good for me, I'm afraid. :lol:

Reply 16

Imperion

17

I was late again :argh:

Reply 17

troubadour.

19

Original post by Imperion

I was late again :argh:

I feel your pain. :console:

Whenever I'm on a study help thread, there's always that pressure to solve it as quickly as possible so I don't end up having to delete my answer because five other people have already explained it. :lol:

Reply 18

Imperion

17

Original post by Hydeman

I feel your pain. :console:

Whenever I'm on a study help thread, there's always that pressure to solve it as quickly as possible so I don't end up having to delete my answer because five other people have already explained it. :lol:

The one time I was early the OP didn't word the title correctly. -_-

Reply 19

jammy4041

18

I also have the consensus answer. Just be sure not to confuse the height of a trapezium (in this case, equivalent to length XY) with the the side equivalent to length AD.

Congrats on getting the answer.

Once again, it's mee

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